全文获取类型
收费全文 | 415808篇 |
免费 | 46825篇 |
国内免费 | 923篇 |
专业分类
463556篇 |
出版年
2018年 | 3903篇 |
2017年 | 3788篇 |
2016年 | 5115篇 |
2015年 | 6912篇 |
2014年 | 8037篇 |
2013年 | 11584篇 |
2012年 | 13089篇 |
2011年 | 13009篇 |
2010年 | 8657篇 |
2009年 | 8093篇 |
2008年 | 11578篇 |
2007年 | 11703篇 |
2006年 | 11212篇 |
2005年 | 10590篇 |
2004年 | 10407篇 |
2003年 | 10066篇 |
2002年 | 9760篇 |
2001年 | 19053篇 |
2000年 | 19200篇 |
1999年 | 15630篇 |
1998年 | 5516篇 |
1997年 | 5788篇 |
1996年 | 5604篇 |
1995年 | 5090篇 |
1994年 | 5212篇 |
1993年 | 5040篇 |
1992年 | 12967篇 |
1991年 | 12407篇 |
1990年 | 12318篇 |
1989年 | 12263篇 |
1988年 | 11160篇 |
1987年 | 10610篇 |
1986年 | 9832篇 |
1985年 | 9880篇 |
1984年 | 8006篇 |
1983年 | 6975篇 |
1982年 | 5291篇 |
1981年 | 4668篇 |
1980年 | 4548篇 |
1979年 | 7660篇 |
1978年 | 5928篇 |
1977年 | 5290篇 |
1976年 | 5113篇 |
1975年 | 5529篇 |
1974年 | 5778篇 |
1973年 | 5700篇 |
1972年 | 5161篇 |
1971年 | 4561篇 |
1970年 | 4031篇 |
1969年 | 3732篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
321.
322.
A seasonal distribution of enteroviruses and adenoviruses in raw sewage effluents of Athens, Greece, was observed over a 15-month surveillance period. All 36 samples tested were positive for both virus groups. Adenovirus concentration levels ranged from 70 to 3200 cytopathic units per litre of sample, whereas the corresponding values for enteroviruses were 90-900 cytopathic units per litre. Peak values for adenoviruses were recorded during the months of April and June 1983, whereas for enteroviruses the peak was recorded in September 1983. All three types of poliovirus were present. Coxsackievirus types B-1, B-2, B-4, and B-5 and echovirus type 7 were also isolated. Adenovirus types 1, 2, 3, 5, 7, and 15 were detected as well. 相似文献
323.
Metabolic depletion of human red cells with 2-deoxy-D-glucose in the presence of EGTA decreased ATP to about 4% of the initial value and increased total ouabain- and furosemide-resistant Na+ and K+ effluxes by 20% and 100%, respectively, and furosemide-sensitive Na+ and K+ effluxes by 100% and 60%, respectively. When ATP was restored, all the components of Na+ and K+ fluxes measured returned to baseline levels suggesting a metabolic dependence. 相似文献
324.
An association between a lymphocyte antigen in sheep and the response to vaccination against the parasite Trichostrongylus colubriformis 总被引:1,自引:0,他引:1
Lymphocyte antigens were tested in sheep which had been selected for responsiveness to vaccination against the intestinal nematode Trichostrongylus colubriformis. These sheep had been bred in an assortative mating programme which produced offspring designated as either “high responders” or “low responders”, with highly heritable resistance or susceptibility.Ovine lymphocyte antigen (OLA) typing antisera were obtained from parous ewes in the course of matings which produced the high and low responder flocks. A particular antigen (SY1) was found to be present in high frequency on the lymphocytes of high responder (72·2%) and in lower frequency (21·9%) on the lymphocytes of low responder rams. In ewes, the frequency for high responders was 65·7% and for low responders it was 33·5%. A similar association between the SY1 antigen and low faecal egg count was found in random-bred sheep which had been vaccinated with irradiated larvae and challenged with normal larvae. The conclusion was drawn that this lymphocyte antigen was likely to be part of the sheep major histocompatibility complex which influenced the immune response of sheep to vaccination against the parasite. 相似文献
325.
J M Allen J P O'Shea K Mashiter G Williams S R Bloom 《BMJ (Clinical research ed.)》1983,286(6378):1607-1609
Ten patients with advanced progressive adenocarcinoma of the prostate were treated with a long acting analogue of gonadotrophin releasing hormone. Eight of these patients responded to treatment in terms of pain relief and clinical regression of tumour. Serum gonadotrophin and testosterone concentrations were significantly suppressed by the end of the second week of treatment, testosterone concentrations being comparable with those achieved by castration. The two patients who failed to respond had both relapsed previously when receiving conventional treatment, and neither showed any endocrine response to the analogue. Superagonists of gonadotrophin releasing hormone may be the treatment of choice in adenocarcinoma of the prostate, but further trials are required to establish long term safety and efficacy. 相似文献
326.
327.
328.
329.
330.